Maternal Occupational Exposure to Organic Solvents during Pregnancy and Infant Visual Processing
| Principal investigator(s): | Joanne F. Rovet (University of Toronto) |
| Co-investigator(s): | Carol Westall, Gideon Koren, ChristineTill (Hospital for Sick Children) |
| Sponsoring Institution: | University of Toronto |
Objectives
The objectives of the study were:
| 1. | to determine whether offspring of women exposed occupationally to organic solvents during pregnancy are at increased risk of visual functioning deficits |
| 2. | to compare intellectual abilities of solvent-exposed and non-exposed infants. |
Rationale
| 1. | Despite a large body of evidence demonstrating that the visual system in an important target for organic solvent toxicity in adults, little attention has been devoted to the visual functioning of children with prenatal solvent exposure. |
| 2. | While reserach on animals and adults describes central nervous system toxicity from organic solvent exposure, studies of children exposed to organic solvents during pregnancy report inconsistent findings on intellectual functioning. |
Methods
| 1. | To test for visual abnormalities in infants with prenatal organic solvent exposure, mothers were recruited during pregnancy through the Mothersisk Program, an antenatal counseling service in Toronto. Their infants were tested in the Visual Evoked Potential (VEP) laboratory in the Psychology Department at the Hospital for Sick Children. The sample consisted of 21 infants born to women who were occupationally exposed to solvents during pregnancy and 27 non-exposed age-matched infants recruited in a similar manner.
A sweep VEP technique was used to assess contrast sensitivity and grating acuity by presenting sinusoidal gratings that ‘swept’ across a range of contrasts and spatial frequencies. A transient VEP technique was used to assess respones tro equiluminant chromatic- and luminance-modulated sinusoidal gratings prersented in pattern onset-offset format. Exposure level was estimated from questionnaire data obtained during pregnancy. Testers were mnasked to exposure status. |
| 2. | To test for intellectual deficits, 32 children (11 exposed and 21 non-exposed) were assessed at a mean age of 16.5 months using the Mullen Scales of Early Learning. All mothers had been origfinally recruited for the visual functioning portion of the study (see Objective #1). |
Findings
| 1. | Occupational exposure to organic solvents during pregnancy is associated with contrast sensitivity loss and increased risk of red-green color vision abnormalities in offspring. |
| 2. | Study results suggest that the intellectual functioning of infants whose mothers had been exposed in the workplace during pregnancy to organic solvents is in the normal range and does not differ overall in intelligence from non-exposed infants. However, exposed females showed a tendency to slightly lower scores on scales of early language skills, and language scores tended to be lower in children whose mothers had higher exposures during pregnancy. |
Due to small sample sizes, however, the data on language skills are preliminary, and larger cohorts are needed to confirm the findings.
For more information
joanne.rovet@sickkids.on.ca
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